Create and configure a feature flag

Feature flags are a foundational component of Unleash, enabling you to manage features dynamically. This guide details the process of creating and configuring feature flags within Unleash. You’ll learn how to create flags, define activation strategies, enable them, and optionally refine their behavior with constraints, segments, and variants.

This guide focuses on the Unleash Admin UI, but you can also use the Admin API to create, update, and manage feature flags:

1
curl -X POST https://app.unleash-instance.example.com/api/admin/projects/projectId/features \
2
     -H "Authorization: <apiKey>" \
3
     -H "Content-Type: application/json" \
4
     -d '{
5
  "name": "disable-comments"
6
}'

Create a feature flag

To create a feature flag in the Admin UI, do the following:

1. Go to a project and click Create feature flag.
2. Enter a unique name for the flag and click Create feature flag.

Add an activation strategy

Activation strategies determine how and for whom a feature flag is enabled within a specific environment (for example, development, or production). To add an activation strategy to your feature flag in the Admin UI, do the following:

1. Go to a feature flag, and select the environment where you want to configure the flag.
2. Click Add strategy, select Gradual rollout, and click Configure.
3. In the General tab, select your rollout percentage. Optionally, you can set the strategy status to Inactive if you don’t yet want the strategy to be exposed.
4. Click Save strategy.

Enable the feature flag in an environment

To enable the feature flag in an environment, use the main environment toggle to enable the flag in the environment. This ensures that the feature flag is evaluated using the rules of its activation strategies and the provided Unleash context.

Refine targeting with constraints and segments

Strategy constraints and segments allow you to apply fine-grained filters to your activation strategies, ensuring they only activate for users and applications matching specific criteria. You can add constraints or segments when creating or editing an existing activation strategy.

1. Go to the feature flag and the environment containing the strategy you want to modify and click the Edit strategy.
2. In the Targeting Tab, click Add constraint.
3. To define the constraint, add a context field, an operator, and values to compare against.
4. Add more constraints if needed, and click Save strategy.

Segments work similarly to constraints, but they are a reusable set of constraints that you define once and can reuse across flags.

Configure strategy variants

Variants give you the ability to further target your users and split them into groups of your choosing, such as for A/B testing.

1. Go to the feature flag and the environment containing the strategy you want to modify and click the Edit strategy.
2. In the Variants tab, click Add variant.
3. Enter the variant name and an optional payload.
4. Optionally, click Add variant again to add more variants.
5. Toggle Custom percentage for fixed weights, if required.
6. Click Save strategy.